In typical DSL or ADSL applications, extended to the solid state drive or hard disk drive application, a plurality of storage capacitors coupled in parallel are commonly used to store energy to support sudden power shutdown, which highly increases the system cost.
Storing the energy in a high voltage form and releasing the energy when the power fails can reduce the amount of storage capacitors. Prior art using the combination of a charge pump and a LDO (low dropout) circuit to achieve the energy management, where the charge pump is used to pump the input signal to a higher voltage and the LDO circuit is used to release the stored energy. However, the charge pump needs many switches, which make the system complicated. But to achieve higher storage voltage, more switches are needed. In addition, the LDO circuit has large power loss during the releasing which dramatically reduces the system efficiency and increases again the system burden.